Thursday, 7 February 2019

Record temperatures in US after freezing conditions


I have found that such extremely rapid rises after such cold is very rare.

5 January, 2019

I have found in going through heaps of data back to 1879 for West Lafayette that when the temperature drops to -15 or less, it tends to stay quite cold for a while.
A set of events tends to precede an Arctic Outbreak episode.  It is usually some colder weather that arrives after a milder spell, followed by a winter storm that lays down snow cover.
The Arctic front usually occurs just after the winter storm, often accompanied by blowing/drifting snow & dangerous wind chills.  A bright, sunny, but dangerously cold day will follow with still strong winds creating dangerous wind chills. 
The coldest night is usually the one just after this sunny day as the wind diminish.
Then, clipper train develops & brings pehaps two or three rounds of minor snowfall over a period of several days as the temperatures moderate.
Eventually, the trough with clippers flattens out & we thaw.
This process usually takes 1 to 1.5 weeks, however. 
Also, these stronger Arctic Blasts tend to go all the way to the Gulf Coast & into Florida.  Often the entire eastern half of the U.S. is in the cold wave.  The brutal cold is usually not limited to just the Midwest or Northeast or Northern Plains, but an all-encompassing Arctic Outbreak that sends a freeze deep into Florida. 

The recent Arctic Outbreak was different & broke tradition with what normally occurs with cold of this magnitude. 
This cold outbreak did not go much farther south than Tennessee & was largely tied up in the Northern Plains, Midwest, Great Lakes & Northeast. It did get colder in the South, but the typical plunge of cold deeply southward that usually occurs with an outbreak of this magnitude did not occur.
The similar 1985 outbreak saw record cold to South Florida & the 1996 event saw single digits to south-central Texas.  An ice storm hit the Gulf Coast in January 1996, as well.  1977 saw snow to the southern tip of Florida.  Our below zero temperatures in December 2004 occurred as historic snow storm hit the Gulf Coast with parts of southeast Texas seeing +12" of snow.............the greatest snowstorm there since the big one of winter 1895 with +20".
This outbreak was in & out in an unusually rapid fashion & brought the extreme cold even with a lack of good snow cover here.  Where there was good snow pack, it was as low as -38 in northern Illinois (new unofficial state record low temperture).
The unusual lack of rapid southward progression of this historic cold & lack of snow cover southward may have allowed it to moderate so quickly as the extreme cold covered less of an area.  This may have been a surface to atmospheric feedback that we see like with heat & drought.

A 73-degree rise from such cold is an extreme rarity.
In going back to 1879, rises of +65 degrees after lows of <-15 in four days only occurs, on average, once every 70 years.
However, a +70-degree rise in 4 days or less with a <-15 cold wave or less has NEVER occurred. 
Jumps of such magnitude usually take at least 7 days, as shown in the 140 years of data.
In the Crawfordsville data of January 1860, the -23 in early January shot up to 66 at in late January.  Impressive, but it took a few weeks.  The same thing have happened in 1864.  Historic blizzard & cold occurred in early January with the coldest New Year's Day (by far) on record with a high of -15 & low of -22 with "a gale" & multiple reports of people freezing to death or loosing fingers & toes, even a nose from frost bite.  Late month saw record warmth & flooding rainfall with high of 66 once again.  This took weeks, however.
January-February 1883 & 1884 saw big jumps like this from -20 to -15 & snow to ice storm & flooding rain with 40s, 50s, even 60.  This warm-up took more than a week, however.  The jump from -33 to 59 in January 1887 took 15 days & the -33 to 50 in January 1885 took 12 days.

The former record largest temperature jump from <-15 in four days or less was 69 degrees set in February 1899.  This occurred at the end of one of, if not the greatest, Arctic outbreaks since at least 1857 in the eastern U.S.
It is definitely interesting to note that just last year, at the end of the historic December 31, 2017-January 7, 2018 Arctic outbreak that we warmed 77 degrees in 5 days from -20 to 57, then back from 59 to -1 in two days afterward!  We went from -20 to 38 in four days, a rise fo 58 degrees.  10 of 12 days dropped below 0 December 27-January 7 of last year! 
Also, December 26-20, 1917 was close to making it into the +65 club with a 62-degree rise in 4 days from -12 to 50 in that historically cold, snowy winter of 1917-18.
So, +65 rise in such a short period after such cold has only happened twice since 1879 at West Lafayette:
1.  69 Degrees
February 13-16, 1899
-20 to 49 in 3 Days
This bore resemblance to our recent cold in terms of wind chill here.  However, this was the Great 1899 Arctic outbreak that saw every state in the South reach state-record cold.  Many of these records stand today, like the -2 recorded at Tallahassee, Florida.  Also, a historic Nor'Easter with blizzard from Georgia to Maine struck. 
Calculating the wind chill from the temperature taken & labled winds in the heart of the cold wave show wind chills reaching -48 at Purdue University.
It was interesting in seeing the extent of the cold of how rapidly it warmed.  This may have had to do with the time of year.  Temperature recover much more easily in mid to late February than mid to late January.  However, late February to early March 1960 saw a historic outbreak of cold here with lows to -15 & the recovery was long & arduous.  It was unusually cold until late March.
We also saw the 1899 Nor'Easter, which usually tends to halt rapid warming in a cold wave.
2.  68 Degrees 
January 16-19, 1972
-18 to 48 in 3 Days
-20 to 48 in 4 Days
This was an extreme event in the extremely rapid onset & intensity of the cold, then the sudden flip to warm.  In fact, in the southern U.S., after record cold, record warmth occurred just days later!
As the cold came in, Casper, Wyoming dropped 76 degrees in 48 hours (36 to -40).  Lander, Wyoming measured a 92 mph wind gust.  Indeed, a testament to the strength & loopiness of the upper jet, Spokane, Washington also had high winds with a measured gust of 59 mph.
Nashville, Tennessee dropped to a record low of -1 on the 16th, only to hit a record high 78 (highest temperature every recorded in Nashville in January at the time) on the 24th.
International Falls rose from -42 on the 14th to 36 on the 17th.
Here is a write-up from NOAA on this remarkable event:

Region Sees Record Warmth Less Than a Week After Freezing Temperatures

These Spring-like temperatures came less than a week after temperatures fell into the single digits, and felt like below 0.

5 January, 2019

Temperatures soared into the upper 60s and low 70s Tuesday afternoon, bringing record highs to several towns. These Spring-like temperatures came less than a week after temperatures fell into the single digits, and felt like below 0.

Trenton crushed their previous record of 64 degrees set in 1890. The high Tuesday was 70 degrees.

Reading crept just past their previous record of 64, set in 1991, with a high of 65 Tuesday afternoon.

In Georgetown, a high of 71 climbed past the previous record of 69. The old record was set in 1062.

Philadelphia didn’t set a record for warmth, but came close. The high Tuesday was 67 degrees, while the previous record is 69 (set in 1991). The average high in Philadelphia for early February is 42 degrees. A high of 67 is more normal around April 23.

Enjoy the piece of Spring while you can, temperatures drop near average by Wednesday!

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